Abstract: The purpose of this ten-week study was to determine the effects of self-assessment and model-listening on middle school chorus students‘ performance achievement. Sixty-four middle school chorus students were assigned to one of the following four groups: (a) Model X Self-Assessment, (b) Model X No Self-Assessment, (c) No Model X Self-Assessment, and (d) No Model X No Self-assessment. Once per week, self-assessment groups completed self-assessments and model-listening groups listened to a model recording. During week ten, each group made final recordings which were evaluated by two judges. Data were analyzed using descriptive statistics to determine differences among the groups for the five performance sub-areas (Tone Quality, Intonation, Rhythmic Accuracy, Expression, and Balance/Blend) and for Overall Performance achievement. Data indicated that middle school choral students benefit most from no-treatment in the performance sub-areas of Tone Quality, Intonation, and Expression, and in Overall Performance. Also, self-assessment alone is the most effective treatment for improving Balance and Blend.